Re: [PATCH 1/2] mm/vmalloc: acquire init_mm read lock on huge vmap promotion

[Lorenzo Stoakes]

On Fri, Jul 10, 2026 at 01:57:46PM +0100, Lorenzo Stoakes wrote:
> As per Sashiko, we need to account for x86's slightly bat... interesting
> ptdump of non-init_mm page tables.

Well it turns out arm64 also traverses EFI ranges which is kinda the saner end
of it ;)

Patch incoming in any case. Will send separately as each patch stands alone and
this series is fine as-is.

>
> The fix is to take a nested init_mm lock in ptdump_walk_pgd(), which is
> safe as nothing depends on an init_mm lock prior to acquiring an arbitrary
> mm's lock.
>
> I think this could potentially be sent as an entirely separate patch, as it
> doesn't change what this protects against, nor the x86 CPA patch, both of
> which stand on their own.
>
> Cheers, Lorenzo

Cheers, Lorenzo